[14] RFR (S): 8235934: gc/g1/TestGCLogMessages.java fails with 'DerivedPointerTable Update' found

[Thomas Schatzl]

Hi all,

   can I have reviews for this testbug where there is a mismatch between 
"C2 compiler is enabled" and "C2 compiler is compiled in" in verifying 
output messages.

I.e. G1 prints some additional log messages if the C2 compiler is 
compiled in, but the test checks this message for (non-)existence if the 
C2 compiler is enabled.

Since there are a few flags that can toggle compiler use even when 
compiled in (UseCompiler, TieredStopAtLevel<=3, ...) the GC prints that 
message but the test does not expect it.

The fix is to add a whitebox method that specifically returns whether 
the C2 compiler is compiled in or not, to be used by the test.

I would like to push this to 14 even if it is P4 because of the test bug 
exemption, returning unnecessary reproducable errors.

CR:
https://bugs.openjdk.java.net/browse/JDK-8235934
Webrev:
http://cr.openjdk.java.net/~tschatzl/8235934/webrev/
Testing:
hs-tier1-3, local runs of TestGCLogMessages.java

Thanks,
   Thomas